Questions tagged [star-formation]

Questions related to the physical processes involved in or to the observations of the process of forming a star.

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Emission Line Galaxies(ELGs) selection using narrow band

I selected ELGs using the z BroadBand and NB921 narrow band according to the condition of Hayashi+11 Then I plot the transmission curve of the filters used, I got this As we can see NB921 and NB926 ...
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Are metallicities of molecular clouds lower in the outskirts of the galaxy?

(this question was originally posted in an answer by user PSR-1937-21 to another post. I find it an interesting one, but since they don't seem to be active anymore, I'm posting it to see if somebody ...
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Why does a hot cloud need more mass to collapse?

I was wondering why does a hot cloud need more mass to collapse than a cold cloud to form a protostar? Is it because there's a higher thermal pressure inside the hotter cloud than it is in a colder ...
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Is it only possible to look at solar systems with stars at least as old as ours to be able to find intelligent life?

Assuming the speed it takes to development intelligent life is the same in all solar systems, would we need to look at exoplanets with stars as old or older than ours to find intelligent life? A young ...
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Supernova impact on Protostar formation

What would be the impact on the formation of a new star (protostar) when a nearby star (within 10 LY) goes supernova? Will the force of the explosion (once it arrives in the Molecular Cloud where the ...
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Why aren't there blue elliptical galaxies or yellow spiral galaxies?

Elliptical galaxies are universally old and yellow; about three-quarters of all ellipticals have no significant star-forming gas or dust left, and even the quarter or so of ellipticals that are still ...
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In Orion, how close in local distance are the closest of the member stars?

All the members of Orion are within the Milky way, and some of them look pretty close to a neighbor. And could the bow* be an effect similar to the Radcliffe Wave? *shield
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Why does the star formation rate correlate with the total stellar mass in star forming galaxies?

The so-called "Main Sequence" of star-forming galaxies (e.g., Brinchmann et al. 2004; Noeske et al. 2007) clearly points to a linear relation between the stellar mass of galaxies and their star ...
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What is the difference between emission line and recombination line?

When an electron jumps from higher level to lower level a photon is emitted. This is seen as an emission line. But what exactly is a recombination line? I found them similar. Can you please tell me ...
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Very Old Stars in the Universe [duplicate]

How could a Star possibly be older than the Universe ? Is this possible or are the calculations off when determining the age of such Stars ? Can a Star exist that formed on its own independent of a ...
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What exactly are infrared dark clouds and what is the significance of the orientation of their magnetic fields?

In the video Why NASA's SOFIA Telescope On A Plane is "Perfectly Balanced" after about 10:04 SOFIA associate director James Jackson says: We have a ...
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How much of a molecular cloud can end up as “starstuff”?

Stars form within molecular clouds. These clouds can be up to 6 millions solar masses. When the cloud collapses into stars, is it possible to know a rough figure for how much of this material actually ...
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Freefall timescale for a Jeans-unstable hydrogen cloud of mass M

I'm working on a project (personal, not academic) that involves calculating the collapse timescales for protostars which will end up becoming stars of varying given masses. I'm treating the pre-main ...
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Will the conditions that allow life to evolve still be around in a trillion years?

Some billions of years ago, systems like the Earth couldn't emerge and therefore life couldn't arise, because not enough of the heavy elements had formed yet. Assuming there'll neither be a big ...
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Estimating a star's radius, temperature, and luminosity based on its mass

(See updated figure and description below.) I've been trying to generate ballpark estimates for the radius, temperature and luminosity of stars in the main sequence based solely on their masses (...
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Characteristics of the first planets in the Universe?

What would have the very first planets looked like, based on their most likely chemical compositions? For example: Were they mostly grey gas giants with atmospheres of hydrogen and helium, ...
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How many parent stars contributed to our solar system? [duplicate]

All of the stuff that isn't hydrogen and helium (which came from the Big Bang), that coalesced to form our solar system (the iron, the sulfur, the water, and so forth) all came from previous ...
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Formation of the First Stars

I've got a few questions about the first stars to form in the universe. First off how might metalicity have impacted the formation of the first stars and also what effect would the absence of metals ...
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How to model and subtract nebular emission lines from stellar spectrum

I have optical stellar spectra from a star forming region with spatially varying nebular background. I want to subtract the nebular lines from the stellar spectra (which are varying in intensity from ...
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What will future populations of stars be like?

As stars slowly using up hydrogen and ejecting heavier elements into space, the future stars will form from nebulae that are more metal and helium rich. The question is: how does the increased ratio ...
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What is the physical reason of the mirror principle in the stellar evolution?

I understand that stars transition into the red giant phase by obeying the mirror principle, as written here: Shell-burning stars obey something called the mirror principle, which is an observation ...
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Stars readjusting themselves in the sky [duplicate]

I had a meeting in the evening and thought of grabbing a snack before that. I stepped out of the office along with a colleague. He was on his phone and I was simply staring at the sky wishing it would ...
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Do stars come on like LEDs or wick lamps? [duplicate]

Is stellar ignition an instantaneous thing - before, dark, after, shining brightly - or more of a process over time? In fusion research 'ignition' appears to be an event, but maybe in a protostar it ...
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What is the most mass that matter likely to form?

If we plot graph between accumulate of forming mass (y-axis) and mass (x-axis), where is the maximum ? There is a story how I get this question. It start when I think about question "Is our sun is ...
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What is the lyman-werner background?

I've seen several papers that discuss the Lyman-Werner Background (LWB) when modeling star and galaxy formation in the early universe. One in particular (https://arxiv.org/abs/1803.04527) even varies ...
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How could a supernova seed solar nebula?

If the heavier elements such as Uranium came from a supernova, then this supernova had to sit somewhere right in the middle of the original solar nebula, because although the ejected matter traveled ...
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Why does star formation cease?

The universe is expected to have a time when star formation slowly ceases. However, this seems bizarre as there is always an abundant amount of matter in the Universe. Massive amounts of hydrogen ...
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Stellar nurseries in the “Shedding New Light on the Whirlpool Galaxy” video

Captions in the Hubble Space Telescope YouTube channel video Shedding New Light on the Whirlpool Galaxy say: (visible) Along the dark dust lanes, bright pink nebulae are the birthplace of new stars. (...
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Could stars form outside of galaxies?

Is it possible for there to be a dense enough nebula to form stars outside of any galaxy? Does a galaxy have a minimum size to produce stars? Or could you have a few dozen stars clustered together by ...
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Activity of M dwarf stars

Why are M dwarf stars the most active (in terms of starspots and faculae) of all stars?
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A few questions regarding the transit of planets

Here we will be concerning ourselves with the transit of a planet with it's parent sun. I have a few questions that I am not sure about: 1) Do all planets transit their parent sun? It would seem to ...
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Remains of the progenitor of the Sun

It has been argued that it is not possible to trace back the remains of the progenitor star of the Sun (sometimes called Coatlicue), which, being estimated in the mass range of 30 $M_{\odot}$, should ...
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Can a donut-shape planet or star be formed?

How stable is that configuration and under what conditions such object may form ? Is there any evidence suggesting that such objects might exist ?
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Is there any definitive proof of stars being “born” in nebula formations?

Is there any absolute evidence of star formation inside of nebulae (AKA stellar nurseries) as is suggested and even stated as fact by many textbooks?
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The formation of new stars as depicted in Feynman's lectures

I've stumbled upon this curious passage addressing the formation of stars in Feynman's lectures on physics: Whether we have ever seen a star form or not is still debatable. Figure 7–12 shows the ...
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What does the ']' in the spectral line “CIII] 1909 Å” mean?

The above emission line, as I understand, is a useful probe of early star-forming galaxies. However, I do not understand what the ']' to the right of the 'CIII' means. I could not find any online ...
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Black-hole becoming a star again - follow-up question [closed]

Some questions have been posed about black holes becoming stars again once they attract enough hydrogen/atomic matter from another star. Some answers were a forceful NO. Never. However - let's ponder ...
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What's the profound reason(s) why the star formation rate drives the scatter of the mass-metallicity relation in galaxies?

Since decades it's well known that a correlation between stellar mass and metallicity (Z; both stellar and gas-phase Z, but here I focus on the gas-phase Z) exists (e.g., Tremonti+04; analysis of >...
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1answer
310 views

Black Dwarf Capabilities

Can a black dwarf be suitable for manned exploration, once it cools down? And potentially used for space mining?
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Star formation around rotating black holes?

Please excuse an amateur question. While trying to think of anything but what was happening during a dental procedure my mind turned to a model of a star close to a rotating black hole and the ...
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Doubt about star formation [duplicate]

When a star runs out of hydrogen, it either goes through supernova or forms white dwarf and planetary nebula. So there should not be much hydrogen left to form a new star in the nebula. So how new ...
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If two white dwarfs collided, would they become a star?

Would the temperatures during such a collision be able to ignite nuclear fusion, bringing the dead star back to life? If so, would it only be able to fuse for a short time before running out of fuel, ...
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Will all of the gas in the universe be converted into red dwarf stars?

Red dwarfs have lifespans of trillions of years and are also the most abundant stars, making up 70% of the stars in the Milky Way. No red dwarf star has ever died and none will die for a very, very ...
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How did the lighter elements end up in the center of the solar system? Solar System Formation

The previous generation of stars famously are the origin of all the heavier elements (up until iron?) in the solar system. So a big portion of the solar system mass actually is made up of Carbon, ...
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If two binary brown dwarfs began to exchange gas with each other, would they both ignite into stars?

If two brown dwarfs got close enough to exchange gas with each other, could it trigger nuclear fusion within their cores? Is it possible for two brown dwarfs to orbit so closely and become a ...
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Term for the moment when hydrogen fusion begins in a star

I have read of this process many times, but I don't think I know the term specifically for the moment when hydrogen fusion begins. What is this moment called?
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How was the Sun formed?

Refer to the below minutephysics video, in which they say that in order to reach the Sun from earth, we must first stop revolving around the Sun ie make our tangential velocity zero, and then head ...
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What are infall signatures in stars?

I came across several papers (e.g. Looking for outflow and infall signatures in high mass star forming regions P. D. Klaassen, L. Testi and H. Beuther, 2011) talking about infall signatures in star ...
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How do we calculate heat flow or cooling rate for no fusion brown dwarf star?

I was reading this article and it said something that didn't sit right with me. "SIMP0136 still gives off light mostly in the infrared wavelengths, as its temperature is now approximately 830° C (1,...
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Spacing of G and K class stars

I was looking at the Wikipedia article "List of potentially habitable exoplanets" and I noticed that many of the closest planets listed(tens or hundreds instead of thousands of light-years away) ...